FRAME AND FORK CONSTRUCTION.
[Illustration: THE KEATING.]
It is a trite but true remark that the modern bicycle is a marvel of
mechanical construction, and certainly no part of it has received more
attention during the past decade than the frame. The frame, with its
braces, rods, diagonal struts, chords and ties, is really a bridge on
wheels built to carry man over the ground. The frame usually consists
of eight pieces of tubing, brazed to either drop-forged or sheet steel
connections; but the latest fads of up-to-date construction vary
even this rule by making the rear forks and also the back stays of a
continuous one-piece construction, these, however, being connected
to the frame by short lugs projecting from the crank-hanger bracket
and seat-pillar bracket. This style, here illustrated, is used by the
makers of the Manson, Iroquois, Hudson, Globe, Colton, and is known
as the three-crown construction. This style of frame has become very
popular.
There are no striking novelties in frame construction for ’98, the few
changes made being in the line of refinement rather than of newness.
High frames are altogether out of style, low frames being the proper
thing, cyclists evidently preferring to ride a low frame with a short
head and dropped crank-hanger and getting the necessary reach by
raising the seat-post.
Originally all bicycles were built with drop-forged connections, or
connections made from steel stampings. During the last three years
sheet steel stampings have been very largely used, but after the frame
is enamelled it is impossible to say what these connections are. On the
old “Ordinary” construction the use of large tubing for the backbone
necessitated the insertion of the forgings into the backbone, thus
producing flush joints. When the lowly Safety came in, with its tubing
of small diameter and thick gauge, external connections were used
altogether, and the tubing was inserted into the connections; but with
the growing use of large tubing, flush joints came into vogue again,
and they are undoubtedly the most popular today.
[Illustration: THE UNION.]
The joints used in bicycle frame construction are of three kinds,
the most popular at present being the flush or butted joint, outside
joints and lapped joints. The flush joint, as its name indicates,
is one showing no connection on the outside, being perfectly smooth
and apparently jointless, and is made by brazing the tube over the
connections, which are made of forgings or stampings. The outside
joint is produced by inserting the tube inside of the connecting lugs
or brackets, which are therefore necessarily larger in diameter than
the tubing. When large tubing is used it does not make as neat a joint
as when tubing of smaller diameter is used, hence the outside joint,
although a good one, has fallen into disfavor since the advent of large
tubing. The lapped joint is made by splitting the tube and cutting away
the centre portion of the tube where split and cutting and brazing it
to and around the other tubes of the frame. All three of the styles
of joints described are pinned or riveted before brazing to hold them
in place while being brazed, and they all are usually reinforced
internally, especially the flush and lapped joints.
[Illustration: THE VICTOR.]
As noted in the previous article on “Tendencies for ’98,” the use of
the dropped crank-hanger bracket is universal. It might be said, in
addition, that if this crank-hanger drop is carried to a much greater
extreme, it will necessitate reversion to the old type—that is, not
having the upper tube horizontal or parallel with the ground. In fact,
there are some signs of that reversion in both directions now, two or
three of the makers not making the upper tube entirely horizontal,
slanting it from the head to the seat-pillar bracket. One or two of
the makers have taken a backward step and slant the upper tube from
the seat-pillar bracket to the head, which has the effect of throwing
the weight of the rider where it does not belong. With the drop of the
crank-hanger has come, however, a shortening of the head. This was
necessary, of course, in order to maintain the horizontal position of
the main tube. As is usual, however, in American bicycle construction,
a few of the makers are carrying this shortening of the head to an
extreme point. The use of flush joints has brought about a refinement,
so to speak, in the method of joining the cluster of tubes at the seat
pillar bracket, the rear stays being offset and cranked, or tapered in
many instances, at this point, which produces a very neat cluster or
group.
Frame construction has passed through many eras of faddism. We have
had the heavy-weight fad, the narrow tread fad, and the light-weight
fad, which might strictly be called a craze. The frame, however, has
survived all these, and ’98 frames are to be commended for their
medium weight and medium tread, the only prominent fad on them being a
dropped crank-hanger and short head. For a long while a great deal of
discussion went on both in this country and in England as to the merits
and demerits of a long wheel base. Wheel bases in 1898 have settled
down to from 42½ to 45½ inches, a fair average being about 43½ inches.
[Illustration: THE CYGNET.]
The first rear driving safety bicycle constructed, the Rover, was
built out of parts such as were used in constructing the “Ordinary,”
as will be noted by referring to the illustration of the Rover used
in a previous article. For three or four years after that the cycle
makers of England and America used the most fantastic shapes and
curves in frame construction, one of the most popular of the straight
line variety being that known as the T-shape; a single bar or stem
ran from the head (which was usually an open one) and was connected
to another bar which crossed it at right angles in front of the rear
wheel, the upper part of this last-named bar or diagonal being used for
the seat-pillar bracket, and the lower part carrying the crank-hanger
bracket, the main tube continuing but divided to form the rear
forks. Necessarily there were no back stays or braces connecting the
seat-pillar with the rear forks.
But all the various forms and shapes were superseded when, in 1891,
Thomas Humber brought out the type which has since then been known as
the Humber diamond frame. This type of frame was first shown at the
cycle show in 1892 by the makers of the Liberty, and it attracted an
enormous amount of attention. At that time the frame was, of course,
much heavier than it is now. Round tubes were solely used; the rear
forks were not offset or cranked; and the upper or main tube did not
run horizontal or parallel with the ground. In 1893 and 1894 the
crank-hanger bracket was slightly raised, the original Humber frame
having a dropped crank-hanger bracket, such as is now so popular. With
the raising of the crank-hanger bracket at that time came the making of
the upper part of the frame horizontal. That style has prevailed ever
since.
[Illustration: THE LIBERTY.]
The makers of the Cleveland introduced the use of large tubing in 1895,
and in 1896 at the New York Cycle Show the makers of the Singer, the
only English bicycle represented at that show, exhibited a bicycle
having D-shaped rear forks and back stays, and it was predicted at that
time by the experts of the trade that in 1897 this D-shaped tubing
for use in the back part of the frame would be the coming thing. This
prediction, however, was not as fully realized as anticipated, but in
1898 the prediction has come to a full realization, a careful census
of the makers showing that more than 50 per cent. of them use D-shaped
tubing for either rear forks or back stays, and some of them use it
wholly in the rear part of the frame. Among the variations in frame
construction might be mentioned the aluminum frame, which is cast in
one piece from an aluminum alloy. Nothing, however, has been gained by
this construction excepting peculiarity, as the frame is no lighter
and is no stronger (if it is as strong) than the regular frame made of
tubing; the makers also produce a frame having a gear case as part of
the frame.
[Illustration: VICTOR SINGLE LOOP.]
The Chilion frame is of wood, with steel connections, and built of
solid rods of seasoned second growth hickory, oak, ash or maple, and
the connections are made of aluminum-bronze of a special composition,
which the makers think is a metal lighter and tougher than steel. The
wooden rods are rivetted to the connection with phosphor bronze rivets.
The principle of the joint is similar to a shovel handle, and it is
here to be noted that no one ever yet saw a shovel handle work loose.
The makers claim that no shocks or vibration will affect the frame,
because the wood fibre absorbs the vibration, and that the frame will
stand up under treatment which would ruin a steel frame, it being
impossible to bend, crush or buckle the wooden rods, and that should
the frame be broken repairs can be made at a fraction of the expense
necessitated by the steel frame.
While all this may be true, somehow or another the wood frame has not
caught on, and we are still in the “steel age” of cycle construction.
The coming of the gear case has evidently caused the makers of the
Racycle to adapt their frame to it. They have, therefore, produced a
frame in which the gear case is an integral part of the frame, since
the frame of the gear case consists of a loop of D-shape tubing brazed
on and made part of the frame in place of the rear fork on the chain
side, which is thus dispensed with. They claim that this gear case also
adds greatly to the strength of the entire frame.
[Illustration: THREE CROWN FRAME.]
The makers of the Andrae make their entire frame out of tapered gauge
tubing, which is 18-gauge at each end for two inches, then tapered to
22-gauge through the intermediate portion, while the exterior surface
is uniform in diameter. They make the following claims for this:
“At the very inception of cycle construction, cycle engineers were
aware that a straight tube of uniform thickness was not right when
made up into a cycle frame, as such a tube is apt to be thin at the
connections because of the operations of filing a brazed joint and
cleaning it by the use of a sand blast before going to the filer.
The consequence is that a thin tube, when brazed and cleaned up
at the joints, may be cut away to a mere film at some portions of
its circumference, and so made liable to break under a very light
portion of the load which the tube at its original thickness could
safely sustain. Until the idea of tapered-gauge tubing was conceived,
mechanics were forced to use the ordinary tubes and had no means
of reducing the total weight of the frame without at the same time
reducing its strength, because the only lighter tube obtainable was
one thinner in every part, and it is not considered safe to make a
braze on tubing much less than 18-gauge in thickness. The tapered tube
avoids all this and gives a distribution of metal perfectly adapted to
the manufacture of bicycle frames, as all structures designed to bear
the maximum of a load with the minimum of weight must have their long
members of varying thicknesses of metal.”
[Illustration: CHILION WOOD FRAME.]
The makers of the Eagle still continue to use what they call their
cold-swaged process in all the joints of the tubing they use. The
process consists of placing a tube inside of a tube, and then cold
swaging the double tube to the required thickness and length. The Eagle
people say that through this method they know exactly how thick their
tube is at every point, and which the makers of tubing as ordinarily
swaged do not.
The Luthy frame is made with outside lap-joint, taper-tongued
reinforcements, which extend along the sides of the uprights and
reaches and brace the frame against both perpendicular and colliding
strain and prevent granulation at the corners by transmitting the
vibration to the centres of the reaches, where the vibrations are
thrown off.
The Iroquois frame is fitted with three-inch eccentric chain adjuster
at the crank-hanger group. The rear wheel is always centred and
provided with two sprockets to allow a change of gear. A peculiar
feature of this frame is that while it is of the three-crown
construction, with forged arched crowns front and rear, and D shape
tubing in the backstays and rear forks, the joints are not flush but
outside joints and nickel-plated.
[Illustration: WOLFF-AMERICAN FLUSH JOINT.]
A few makers are still making cushion frames, which were largely shown
by a number of makers at the cycle shows of 1897. Before the advent of
the pneumatic tire there was some reason for the use of cushion and
spring frames, but certainly with the comfortable seats now made and
the pneumatic tire in addition, cushion frames of any sort are uncalled
for.
The Carlisle Manufacturing Company, in order to give increased drop to
the hanger, are producing a cycle having a thirty-inch rear wheel. The
makers of the Rambler are making a man’s heavy-weight roadster having
thirty-inch wheels both front and rear.
[Illustration: CRESCENT FLUSH JOINT.]
The makers of the Clipper show a variation of the three-crown
construction, inasmuch as they do not use the continuous one-piece
rear fork construction, and use what they call a blade reinforcement
straight tapered rear fork, the rear forks being brazed to a lug which
forms part of their patent elliptical truss crank-hanger, and they
claim that through this construction they have sufficient clearance
for a tire as large as 1⅞ inch, that a front sprocket as large as
twenty-five tooth can be used, fitted to a 4⅜-crank axle, with ball
races three inches apart, and with tread 4¾ inches over all. They
claim that this method of construction is an improvement over the old
method, where in order to get a tread less than 5⅜ inches the rear
forks must be bent, which prevented properly reinforcing a vital point
and consequently weakened the frame. They also claim that under the
old method the crank bracket would have to be extended, a process
which is undesirable because more length must be added to the chain,
and the wheel base must also be lengthened, thus adding weight without
strength; also that there was a coming demand for larger tires and
sprockets, neither of which could clear the forks of a wheel with
forty-four-inch wheel base and straight forks, both of these last
being, for good reasons, mechanical features of no little value.
The Keating frame curves the diagonal stay just before it reaches the
crank-hanger and the Racycle also show one model of this style.
In the Luthy frame the diagonal stay instead of being brazed to the
crank-hanger bracket is brazed forward of it, on the lower main tube.
[Illustration: COLUMBIA FORK CROWN.]
The makers of the Wolff-American and the Howard do not believe in
raking the diagonal stay as much as some others do. Both of these
makers make the head of the frame at an angle of twenty degrees from
the perpendicular in order to produce easy steering qualities, and they
bring the angle of the diagonal stay only sixteen degrees from the
perpendicular, thus bringing the rider more directly over the pedals,
which is the popular position at present.
[Illustration: CRESCENT FORK CROWN.]
The truss frame, as used on the Fowler and America, is produced by
dividing the diagonal stay midway between the seat-pillar bracket and
crank-hanger bracket into two parts, these two parts running down to
the crank-hanger bracket.
The Cygnet is another peculiar frame, and is best described by the
illustration, but is interesting mainly as a novelty. It makes a very
taking and graceful looking ladies’ wheel, the entire frame having two
tubular connections, as against twelve in the old diamond frame. The
rear portion of the frame is constructed of two sections of tubing
only. No wood or metal chain or wheel guards are necessary on it, the
rear wheel and all the driving mechanism being within two sections of
frame, so that the skirts of the rider are fully protected.
The makers of the Wolff-American still continue to use their process
of spring tempering to which every frame is subjected. The process has
not been publicly revealed, but they state that the finish and temper
are the same as they put upon the finest clock and watch springs; that
their frames are treated with the same care and delicacy as those
springs are, and that repeated tests have proved the increased strength
resulting from this process of spring tempering, which also renders
every tube in the frame (their tempers always varying originally) of an
equal temper and gives life to the frame and at the same time preserves
its rigidity.
The makers of the Northampton claim to drop the top tube one inch from
seat-post to head, their only claim for this being that it enables
the rider to use a high frame if desired, and gives a very graceful
appearance to the wheel.
[Illustration: LYNDHURST FORK CROWN.]
[Illustration: ARCH FORK CROWN.]
JUVENILE BICYCLES.
The Western Wheel Works, the Crawford and the Featherstone all produce
miniature models of their regular product for juvenile use. Only
one concern (the makers of the “Elfin”) confine themselves strictly
to making juvenile bicycles. They build a cute little diamond frame
for boys in four sizes of frames and wheels, and a double-loop drop
frame for girls’ use in the same number of sizes; they also build a
diamond tandem and a combination tandem. Their product is distinctively
juvenile in every particular, even to the cork grips at the ends of
the little handlebars. They use a reversible crank bracket and chain
adjuster, by means of which an adjustment of 2 inches in the distance
between seat-post and pedals is effected, so that an “Elfin” may be
made to last a growing child for several seasons. This is a decided
advantage in this type of construction, because in a year or two the
youngsters outgrow the regular type of child’s cycle.
LADIES BICYCLE FRAMES.
[Illustration: CRAWFORD FORK CROWN.]
There are no novelties in frame construction of bicycles for ladies’
use. The double-loop frame, like the arched crown, seems to be the most
popular one with all the makers, both East and West, only one other
pattern being largely used, and that having a straight lower main tube
and a curved upper tube, as used by the makers of the Humber, Stearns
and others. The makers of the Columbia, Liberty, Wolff-American,
Keating, Crescent, Crawford, Eagle and many others use the double-loop
style altogether. The Victoria seems to be the only single-loop frame
in the market, but even the makers of the Victoria make a double-loop
frame this year. Many reasons have been advanced why bicycling is so
popular, but certainly nothing added so much to its popularity as
the invention of the drop-frame safety for ladies’ use by Owen of
Washington in 1888.
The old “Ordinary,” of course could be ridden by men only, and
therefore cycling was always regarded by the feminine portion of the
community as a selfish sport, but with the invention of the ladies’
bicycle this objection was removed, and the sport became one for
all people. In former years makers made about 10 per cent. of their
product for ladies’ use. It is safe to say now that 40 per cent. of the
product is now made for ladies’ use, and a great deal of attention has
been paid to constructing a bicycle, particularly among the Eastern
makers, that a lady could mount and dismount from readily. The majority
of the Western makers have for some years past failed to note these
tendencies, and continued building all sorts of straight-frame cycles
for ladies’ use with a very high crank-hanger; these could not be
marketed readily in the East, but for the coming season all the makers
have seen the handwriting on the wall and they are all building with
low-dropped crank-hangers in both styles of frames.
FRONT FORKS.
[Illustration: HUMBER FORK CROWN.]
Front-fork construction in 1898 shows a decided reversion to the old
type used on the “Ordinary,” where all the front forks were of the
arched crown construction. The makers of the Rambler, who also built
an “Ordinary,” have persistently and consistently used this arched
fork construction, and to them must be given the credit for its
reintroduction. It has not only taken the Western makers by storm, but
it has captured the fancy of very nearly all the Eastern makers. A
careful census of over one hundred makers shows that fully 75 per cent.
of them are using some form of arched crown construction, but even in
this arched-fork construction there are a few variations. The Rambler,
the originators of it, use it with outside spearhead reinforcements.
A notable departure in this form of construction is shown by the
illustration as one patented by Fauber, who is also the inventor of
the one-piece crank axle. He makes the front fork, crown and stem of
two pieces of D-shape tubing, bent to shape, and brazed together the
full length of the stem, one of the most taking and strongest forms of
stem connections known. Some of the makers use a drop-forged arched
crown, to which the stem and fork sides are brazed. The Western Wheel
Works, the makers of the Crescent, who first introduced sheet steel
stampings in bicycle construction, and still continue to use them, make
their fork crown of three pieces drawn and stamped together. A few
of the makers still continue to use the good old-fashioned two-piece
flat plate crown, which was invented by Thomas Humber a quarter of a
century ago; and among the distinctive fork crowns to be noted are the
“Columbia,” “Liberty,” “Orient,” “Union,” “Victor” and “Lyndhurst.” The
World and Adlake use three-piece flat crowns. The Victor fork sides
are remarkable, because for many years past all the great makers have
invariably advertised their fork sides as being made of cold-drawn
tubing, flattened to an oval shape. The Victor people claim, however,
that for years past they have made their fork sides of crucible sheet
steel, which are brazed together and reinforced by a steel wire running
the entire length of the rear end, and are brazed to a solid forged
steel crown. But this is the first season they have announced in their
catalogues that they use it.
[Illustration: MONARCH FORK CROWN.]
Another popular method is to make front forks of continuous tapered
one-piece tubing, which is brazed to the fork crown. The majority of
forks of this shape, however, are of D-shape section on the inside and
flat on the outside. The most prominent people using this method of
construction are the makers of the “Union,” used by Jimmie Michael in
all his rides, an illustration of which is given herewith.
One-piece forks are tapered as follows: Sixteen-gauge at the top where
the crown sets, 20-gauge in the middle of the fork side and 18-gauge at
the fork or axle ends.
In the earlier forms of fork construction some peculiarities were
noted; the Warwick Company, for instance, made front forks that were
perfectly vertical. Now all forks are built with considerable rake to
them. On some of the ordinaries forks were built known as the “double
hollow” fork, being fluted. Variations in this consisted of two small
tubes brazed together. The rear forks of some of the ordinaries first
built were known as semi-hollow, being really nothing but a piece of
sheet steel having flanged edges, and on some of the early types of old
velocipedes built the fork was only on one side of the wheel and the
elevating influence of the stage was felt at that early period of its
history, because Hanlon, the actor, in 1868 took out a patent for a
bifurcated fork.
[Illustration: ORIENT FORK CROWN.]
A few makers still use the old-fashioned single piece straight fork
crown, the corners of which, however, are rounded so that they more
closely resemble the popular arched crown. The arched crown has a great
deal to commend it to popular favor, following as it does the shape
of the lines of the tire and rim, and it is now made broader and more
proportionate to the size of the tubing used in the frame. The arched
crown has always been very popular not only in the bicycle, but in
other mechanical and architectural constructions, the Etruscans having
early introduced the use of the arch.
The Sterling Company have always used the arched crown and have done
much to popularize it. Indeed, it would not be too much to say that the
Sterling people are entitled to whatever credit is due the popularity
of this idea in fork crowns. It has been used in Sterling wheels
continuously for several years past, and will unquestionably be adopted
by many leading makers during the present season. When properly made,
the arch fork crown has everything to commend it—strength, style, and
grace and beauty of line. That its largely increased use this year is
due to a direct demand upon the part of riders is undoubtedly true.
[Illustration: UNION FORK CROWN.]
Tubing of 16-gauge is used to make a fork stem, and some of the makers,
for safety, are using as thick a gauge as 13 this year.
The makers of the Lyndhurst show what they call a “Triple Front Fork,”
for which they make the following claims:
“By pressing with your foot on the pedal of a wheel made with a single
front fork you will be surprised to see how much sway or side strain
there is; this is because the power is not applied on a direct line,
but at right angles; this side strain does not stay there, but travels
through the tube up to the front fork, which, having only a single
stem, rocks and has side play. With the square truss in the triple
front fork we claim to stiffen the neck and fork sides so that a great
deal of the side play is overcome.
[Illustration: LIBERTY FORK CROWN.]
“In a single front fork the handlebar is clamped to the fork-stem,
which goes through the neck of the frame, and as you pull and haul in
climbing or against a head wind, the power applied is not felt until
the twisting strain is taken up inside of the neck and localizes at top
of fork crown. By using the truss crown in the triple front fork it
enables us to lock the stem of the fork crown, and the strain localizes
at the top of the triple fork, instead of at the lower end, insuring
greater rigidity and power.
“Sit down violently on the saddle and a single fork springs forward
fully half an inch; the triple front fork carries the strain in a
direct line up to the top of the crown and the strain is diffused
throughout the entire fork and frame.
“In turning corners or upon a lumpy road, a stiff front fork has a
decided advantage, but we claim it is good on asphalt, because of the
decrease in twisting strain, enabling the wheels to track and not sway
out of alignment.
“The above claims are for increase of power, but the strength of the
triple fork is three times that of the single fork, which is a source
of satisfaction in coasting a steep hill.”
[Illustration: WORLD AND ADLAKE FORK CROWN.]
TUBE MAKING.
The air is filled with the vocabulary of the bicycle makers and their
agents and salesmen. Every one of them talks of cold drawn weldless
steel tubing, drop forgings, stampings and brazing. Their catalogues
and their advertisements teem with the same thing, and the cyclist who
has heard and read these terms necessarily feels as if he would like to
know what they all mean. Tube in its original shape consists of a solid
billet of Swedish steel, this being the only quality that can be used.
When the tube is made from a solid, the billet is about four inches
in diameter and six inches in length. When it is made from a hollow
ingot, a piece about three feet long and about four inches in diameter,
with about half-inch walls, is used. These pieces are cast. When solid
billet is used, the core is practically either pushed out or drilled
out to produce a rough tube. This is done while hot, and the hot
pressure is continued until the tube is about four or five feet long;
the diameter then is about 2½ inches, with proportionate thickness of
walls.
The tube is then taken to the cold draw benches. Draw benches, so
called, are of two kinds, either operated by hydraulic or chain power.
In the case of the hydraulic bench, an immense plant is required to
produce the enormous pressure required, approximated at about 2,500
pounds to the square inch. This power is applied through a cylinder
three or four inches in diameter and about eighteen feet long,
operating a piston. The power is so arranged that the piston can be
made to either go forward or backward. The operator crushes down one
end of the tube to be drawn, to make it small enough to pass through a
die, and the tube is then grasped in a grip held by the piston. As the
bench moves the tube passes through the die and becomes smaller. Inside
of the tube and flush up against the die is kept a mandrel, over which
the shell of the tube passes in going through the die. This mandrel is
placed in the tube to keep the shell or gauge from thickening up, and
also to produce a thinner gauge when required. Each operation reduces
the diameter about an eighth of an inch. It is not possible to reduce
the gauge at the most more than 5/1000 of an inch at a time, and this
is very severe treatment. Between each drawing in the cold process the
tubes are annealed, the operation of drawing hardening them. After
annealing they are pickled in a solution of acid and water. The tubes
are then washed in clear water; then they are immersed in oil, and are
ready to be drawn over again. This process is repeated until such time
as the tube reaches the desired gauge and outside diameter. The tubes
are then straightened and the ends cut off, and they are ready for
delivery.
The Pope Tube Company hold the exclusive license in the United States,
however, for a process of annealing steel tubes in iron cylinders about
a foot in diameter and 12 feet in length. These retorts hold about
100 to 150 tubes, and being charged with these are sealed up at the
end and placed in a furnace. The advantage of this method consists
in that the tubes being placed in the retort do not come in direct
contact with the flames, which form a scale upon the surfaces and
require the subsequent operation of pickling the tubes in large vats
of acid in order to remove the scale. This process of annealing in
the retorts usually takes about forty minutes, and necessarily in the
process of drawing a tube before it reaches the proper size it must go
through the process of annealing from five to eight, or even ten, times
before being finished. The only difference between the operation of a
hydraulic draw bench and of a chain bench is that in the chain bench
there is a continuous chain, operated by steam power, and the grip is
so arranged that it will catch in any link desired. Seamless tubes are
made from 1/32 to 10 inches in diameter. Gauge, or thickness of shell,
is measured according to the standard British wire gauge. Bicycle
tubes run from 26 to 10 gauge. The standard gauges used in bicycle
construction for 1898 run from about 16 to 22.
[Illustration: CLEVELAND FORK CROWN.]
It takes fifty thicknesses of 22-gauge tubing to make an inch. Experts
in the trade say that tapered gauge tubing is the coming thing in
bicycle construction. By this term is meant that style of tubing which
is heavy where strain is greatest and light in weight where there
is not so much strain. The outside diameter of the tubing, however,
remains the same all the way through. This is opposed to the ordinary
even-gauge tubing or tubing of uniform thickness of shell. Weldless
steel fork sides are made out of the straight tubing already described,
the first operation consisting in drawing the tube to the proper
tapered design. It is then, by a series of operations, brought to the
flattened or oval shape. Other operations are also necessary to produce
the required curve in the fork. The smaller end which receives the axle
of the wheel is flattened together by another operation. The making of
a weldless steel fork side usually takes from five to seven operations,
according to the shape desired.
The Mannesman tubing, which is made in Germany and was the first kind
known to be used for bicycles in this country, is made by an entirely
different method from any other. Until recently the making of tubing
was so restricted that those owning tubing mills were very secretive
about their processes, and not one cycle rider or manufacturer out of a
hundred has ever seen the material made out of which the frame of his
machine is constructed. They begin with the billet of steel like the
English-American makers, but it is not exactly the same material. They
do not use the Swedish steel, but a metal turned out by themselves. It
is, however, a soft form of steel, like the Swedish or Norway article.
The billets are made up in lengths of three feet and are about two
inches in diameter. First the metal is heated and then put into a
rolling machine. This is a special device used only in their plant
under patents. It consists not only of the ordinary roller but of two
conical rolls, and they are set together on axles, which instead of
being parallel are oblique. The points of these conical rollers are
in opposite directions, of course, and by the peculiar action thus
obtained the outside skin of the heated metal is peeled and spun over
the inside in a spiral fashion, much as a rope is twisted. It is
practically a huge spinning with hot metal. After this single rolling
process, the new formed tube is subjected to two drawings in a mandrel,
in practically the same fashion that American tubing is treated, until
it is reduced to the required diameter and gauge.
A billet of the size described makes a piece of tubing an inch and a
quarter in diameter, of gauge fourteen, or about one-twelfth of an inch
thick. An essential difference between this process and the one used in
this country is that here there are only two drawings and no annealing,
where other processes necessitate a dozen and sometimes a score of
solid drawings. It is claimed that with only two drawings the fibre of
the steel is better preserved. The fibres are not shortened or made
brittle, as they are by repeated drawings.
[Illustration: VICTOR RACQUET FRAME—1892.]
Very little tubing is now imported to this country, our American makers
now being able to supply all the demand, and of the highest quality.
With the improved methods of manufacture has come an improvement in the
quality of the steel for making tubing. It was formerly necessary to
use a very soft steel in making tubing, but the American makers are now
able to turn out tubing from fifteen to fifty point carbon. Right here,
however, should be explained the meaning of this trade phraseology.
For instance, the term “fifteen point” carbon is applied to steel
which contains carbon to the extent of 15/100 of 1 per cent., and
other numbers are used in the same way. Unquestionably the high grade
carbon tubes possess a great superiority over the lower carbon grades
because they possess a maximum of endurance under vibratory strain,
and still are soft enough to resist the shattering effects of a heavy
blow. Popular interest in tubing now centres very largely in the tubing
known as the 5 per cent. nickel tubing, and its method of manufacture
is described in _McClure’s Magazine_ by Mr. Cleveland Moffett, in a
visit to the Pope Tube Company’s works at Hartford, Conn. He says:
“The company has recently concluded, after exhaustive experiments in
the testing department, that it is possible to obtain the very best
results from the use of tubing drawn from steel containing 5 per
cent. nickel, an alloy of the same class as the famous nickel-steel
used in armor plate constructions for the Government.” Of course, the
exceptional hardness and toughness of this kind of steel occasion
great difficulties in its reduction, and call for special and powerful
machinery, and for special skill for all stages of manufacture. So
slow and expensive has been the drawing of this nickel-steel tubing
that up to date the product has been exceedingly limited, so much so
that the mill has undertaken to supply only the Pope Manufacturing
Company with steel of this quality. The main difficulties in working
this nickel-steel come in preparing it for the draw benches. In
them it is treated very much as the “fifty” carbon billets are, but
before reaching them it requires almost as much handling with as many
elaborate processes as the Swedish billets receive in their entire
journey through the mill. The nickel-steel comes from the works of
the Bethlehem Iron Company, and is rolled into plates about two feet
long, one foot wide and one-tenth of an inch thick. These plates are
first punched into disks about a foot in diameter in a blanking machine
that weighs four tons, and bites through the cold steel as a housewife
stamps out biscuits. These disks are then put through a number of
hydraulic presses, even heavier than the blanking machine, and are
forced through dies by powerful rams. The first operation brings the
disks to the shape of a shallow basin; the next makes it an elongated
cup; the next makes it still longer, and so on, until finally it is
reduced to the form of a tube, two feet or more in length. Then the
rounded end of the tube is sliced off, and the nickel-steel is in the
form of a billet ready for the draw benches.
“Simple enough these processes seem when one sees them going
smoothly; but it took months of patient toil, with many mistakes and
disappointments, before the company learned the right way of ‘cupping’
these disks into billets. And today the museum of the tube department
bears record of the many failures in cups crushed into fantastic
shapes, some with ragged sides, and in tubes of nickel-steel deformed
in many ways and torn apart in drawing.”
MAKING DROP FORGINGS.
A drop-forging differs from a hand-made forging because it is made from
a bar of steel suitable for the purpose required and formed in dies
placed in drop hammers, this bar of steel having been previously heated
to the proper degree in a furnace adjacent to the drop hammer which
is used. A drop hammer may be described as follows: The main part of
the machine consists of a heavy anvil, or base, weighing from 7,000 to
30,000 pounds, depending on the size of the hammer. To this is attached
two vertical uprights, between which the head or ram of the hammer
works. On the top of these uprights is the lifting mechanism, a board
being attached to the hammer and the rolls that revolve in the head
act upon this board and lift the weight by friction. In the base first
mentioned are fastened the lower dies, the upper die being attached to
the hammer. In these dies the impression for the forging wanted is cut
by skilled mechanics, the dies afterward being tempered to make them as
hard and durable as possible. The piece of steel having already been
heated to a white heat, is held on the lower die by the workman, who
then operates the drop hammer by means of a foot treadle, the hammer
with the upper die dropping by gravity and forcing the heated metal
into the impressions cut in the dies.
[Illustration: THE STEARNS.]
The surplus metal which has protruded between the lower and upper dies
resembles a fin or web; this has caused the forging to be mistaken
for a casting of iron, because the fin resembles in no small degree
the gate or connection between castings when moulded. This fin of
metal is trimmed off from the forging by means of another machine,
called the trimming press, to which are fitted dies for this purpose.
Experts in the trade say that no “hand-made” forgings or “castings” can
ever wholly take the place of drop forgings in bicycle construction.
Drop-forging manufacturers say that hand-made forgings are obsolete,
owing to the enormous cost of manufacture.
[Illustration: WOLFF-AMERICAN LAPPED JOINT.]
Malleable iron castings, or steel castings, are used by some of the
makers, but entirely sub rosa. They are apt to be full of blow holes
and other defects and not at all reliable, and the maker of high-grade
bicycles who advertises that he uses such castings in his bicycles will
soon find himself out of the market with his product entirely on his
hands.
SHEET STEEL PARTS.
Sheet steel parts, such as are used in bicycle construction, consisting
of cups, brackets, crown heads, etc., when made from sheet metal are
stamped in presses from dies. These presses stand about 6 feet high,
2½ feet square, and weigh about 4,000 pounds. They are operated by a
large driving pulley and belt, the motion being given by means of an
automatic clutch. They can be placed on the floor of any building,
owing to the fact that they do not have the jar that is incident to
“drop” press work.
[Illustration: THE CLEVELAND.]
The blanks are first cut out of cold sheet steel, thereby avoiding the
expense of heating them. They are then placed between dies which have
been previously made to form the required design and shape, but are not
as a rule completely struck up or formed at one operation, the minimum
number of operations necessary to form the complete article being one
or two, and the maximum being from five to seven. The parts are often
annealed between the operations, as the pressure has a tendency to
harden the metal.
[Illustration: REMINGTON FLUSH JOINT.]
The makers and users of sheet steel parts claim for them as advantages
over drop forgings that they are of uniform size, shape and gauge; that
they weigh less; that there is but little waste of material, and that
as many as ten thousand operations can be done by one operator in a
day. Of course, the cost of production is thus made lower as compared
with the cost of production of drop forgings, which require a large
amount of machining on lathes and other milling machines, necessarily
slow in operation. The makers of these stamped form-drawn parts claim
that through the largely increased use of their goods American makers
have been able to produce lighter bicycles than they were formerly able
to produce with the use of drop forgings for their connections, that
the popularity of the bicycle in this country is due to the present
popular prices at which they are sold, and that these popular prices
are largely due to the low cost of sheet metal parts. They also claim
that after the sheet metal parts and the tubes of the bicycle are
brazed together, they then form one continuous piece, to all intents
and purposes as good as if a solid drop forging were used. The average
thickness of the sheet steel used in making these stampings is from
1/16 to ⅛ of an inch. Some very remarkable forms are produced in steel
stampings, notably a crank-hanger of 2 inches in diameter, having
two projections or lugs to carry the rear forks, and the two outer
projections or lugs to carry the large lower main tubes and the large
diagonal stay of the bicycle frame.
CRESCENT SHEET STEEL PARTS.
Until the cycle show of 1895 but little else had been heard of for
making frame connections except drop forgings, but a revelation was
placed before the eyes of the master mechanics of rival cycle making
concerns who visited the show when they inspected the ’95 models of
the Crescent, made by the Western Wheel Works of Chicago. Here were
shown for the first time steering head connections, crank-hanger,
seat pillar and rear fork ends all made of sheet steel and brought to
perfection by a combination of the methods of stamping, drawing and
forming. But even these parts did not surprise these experts of the
trade so much as a sprocket wheel shown. Here was a sprocket wheel
struck up out of a flat disk of sheet steel, its edge turned and drawn
over, thus doubling the width of its face, and on this double edge
were afterward milled the teeth. Of course, the parts shown in those
days conformed in general outline to the construction then in vogue.
The Crescent people, however, have continued to use this method of
making frame connections; and while a large number of other makers
have adopted this form of construction, they, as the pioneers of it,
are still the leaders. Their production is enormous, their gross sales
last year being 83,000 bicycles, and certainly if this method of making
frame connections were not closely akin to absolute perfection their
troubles under the guarantee would be enormous, and would swamp them.
This year their frame connections are all of the flush joint style. The
head connections are formed out of sheet steel reinforcements, having a
large bearing and brazing surface.
Their crown is formed of two pieces of sheet steel drawn to a hollow
arch shape. These two pieces are placed together and the ends come into
a spearhead of capital letter A shape, two holes being drilled on each
side in order to allow the brazing spelter to flow through the crown
freely when the forksides are brazed to them. Before these forksides
are brazed to the crown, however, a third piece of arch shape steel is
forced down over the two pieces forming the crown. This third piece
of sheet steel is lapped underneath the bottom of the crown, so that
when the three pieces are brazed together they practically form one
continuous piece. A drawn lug projects over the top of the crown, and
into this the fork stem, the end of which is shaped to conform, is set
on top of the crown and pinned and brazed to the lug and crown.
Inside of this fork stem, in order to strengthen it, is also placed a
sheet steel liner, extending six inches into the length of the stem.
The whole construction of this fork crown and stem is one of the
strongest in use.
A test made of this form of fork construction at their works showed
that by supporting it horizontally on a frame, the supports being about
six inches above and below the crown, it sustained a weight of 3,500
pounds without deflection.
THE CRANK HANGER.
The crank-hanger is of the one-piece construction, and is made from a
five-inch disk of sheet steel, which is drawn into the shape of a tube
through the medium of five separate operations; and this tube, when
finished, is about two and a half inches in diameter. The four lugs
to carry the rear forks, lower main tube and diagonal stay, are then
drawn and formed upon it, this, however, requiring a total of twelve
operations to complete it. The part requires annealing after every
operation, the process of drawing and forming having a tendency not
only to lengthen the fibre of the metal, but to harden it. The quality
of the metal used in making this hanger must necessarily be of the
best, and after the metal has survived all these operations it must
also necessarily be perfect, for any crack, seam or flaw in it makes it
useless and consigns it to the scrap heap.
[Illustration: MAKING CRESCENT CRANK HANGER. STAGE 1.]
[Illustration: MAKING CRESCENT CRANK HANGER. STAGE 2.]
[Illustration: MAKING CRESCENT CRANK HANGER. STAGE 3.]
[Illustration: MAKING CRESCENT CRANK HANGER. STAGE 4.]
[Illustration: MAKING CRESCENT CRANK HANGER. STAGE 5.]
The seat-pillar lug or group, while not altogether seamless, is of the
one-piece construction, also having the three lugs drawn and formed
upon it. The rear fork jaws are also stamped out of crucible sheet
steel, and are of what is known of the semi-hollow construction.
The little brace which is usually placed between the rear forks and
back of the crank-hanger and called a bridge, is generally made by a
short piece of tubing and brazed to the two rear forks. The makers
of the Crescent, who use a D-shaped rear fork, which is drawn to a
round shape where it is offset and where it joins the rear lugs on
the bottom bracket, make this bridge of two pieces of sheet steel,
which are pinned and brazed together and are carried down on each
side of the rear forks for several inches in a peculiar lipped shape.
It is an expensive method of bridging the rear forks, but greatly
adds to the strength at this point and prevents any serious lateral
deflection of the frame when the pressure is applied to the cranks on
either side. They are the only makers who form their sprockets out of
a piece of crucible sheet stamped steel. As it is now made to fit a
three-sixteenth chain, which is so popular and which they use, they do
not show the wide opening on the flanges of the sprocket between the
teeth.
[Illustration: WORKING DRAWING DIAMOND FRAME MODEL. (See Page 52).]
Fig. 1 shows the circular steel blank as made by the first operation
on a large double action drawing press. It is then drawn into a cup
shape as shown in fig 2. The practicability of the result obtained is
noticeable at once. The edge of the cup is smooth, and there is no
wrinkling, cracking or buckling in the steel, and it is still of the
same thickness as the original sheet. It is again drawn by successive
operations into a cylindrical shape as shown in fig. 3. The end is
cut off, and the next operations form the lugs as shown in fig. 4,
until the final operation gives the result as in fig. 5, when the
crank-hanger is ready for the joining of the frame tubes. It requires
ten days to complete a finished crank-hanger. A marvellous piece of
work this certainly is, and it is doubtful if the result obtained in
stamping this crank-hanger can ever be equalled by the working of
forgings, and the whole result might be summed up by saying that it is
“distinctively Crescent.”
BRAZING.
After the drop forgings or stampings are carefully finished by hand
or machine, they are carefully cleaned to remove any scale or oil.
The tubes having been cut to a proper length, are then closely fitted
into the open joint of the forging or stamping connection. In order,
however, to hold them securely in place they are pinned through. They
are then taken to the brazing furnace. This furnace consists of an
open stand, about three feet high, covered with fire brick, pumice
stone or coke the purpose of which is to retain the heat. The heat is
produced by a mixture of atmospheric air and gas or gasoline, which is
controlled by the operator, and supplied by a blower or fan. The flame
is applied directly to the joint which is to be brazed by a steel tube,
resembling a Bunsen burner, and uses about nine parts of air and one of
gas. The combustion or air and gas in the brazing apparatus is about
the same mixture as is used in a gas engine. The joint having been
brought to the necessary heat, which must in a large measure be left to
the judgment and experience of the operator, powdered borax is applied
first, the object being to remove any oil or other foreign substance
which might interfere with the uniting of the two metals. The borax on
being applied flows almost like water. The spelter is then applied,
producing a flux, and owing to the expansion of the connection and the
tube it readily flows between the joints. The whole operation after the
required heat is obtained usually occupies five or six seconds, the
object being to secure a joint as rapidly as possible, provided the
brazing metal is equally distributed. The gas is then shut off. The
supply of air is continued only in order to rapidly cool the joint,
the object of this being to prevent the flux from disintegrating and
losing its position in the joint. If a brazing has not been rapidly
and properly cooled the jar and vibration which the frame receives
when in use on a bicycle is apt to cause particles of the flux used in
brazing to become loose and rattle in the tube. Necessarily under this
operation what might be termed a congregation of scale and the brazing
flux is gathered on the outside of the joint. This is afterwards
removed by the use of sand blast or pickle, and last, but not least, by
hand filing.
[Illustration: WORKING DRAWING DROP FRAME MODEL. (See Page 52.)]
What is known as “brazing spelter” is really a misnomer, and should be
called brazing solder. Spelter is the crude product from which refined
zinc results. Brazing solder is a combination of copper and spelter
first cast into slabs or ingots, then placed into large mortars and
pounded by a heavy pestle by hand, and, strange to say, that in all our
recent developments in metal work no method can be found to supersede
this method of manufacture, as this is the original method of making it.
There are altogether about eight grades of brazing solder, ranging from
what is known as the coarse long grain to extra fine grain.
The first result of the pounding operation is the coarse long grain
which comes out almost in shreds; by further pounding the shreds are
produced, and the result is the fine long grain. From this operation
comes the rough grain, the first being coarse long grain, the next
medium, then fine and finally extra fine. The proportion of extra fine
long grain to the other coarser grades or varieties is only about
ten per cent. of the total, consequently making the latter grade the
highest in price. The various grades are separated by sifting through a
sieve. The running qualities of this solder are affected by the larger
or smaller proportion of copper used in the composition. The more
copper used the more heat required to melt it, the reverse being the
case where more spelter than copper is used.
On bicycle frame work where the surface is largely exposed, the coarse
varieties can be successfully used, but for the fine work where little
heat can be used, and where the tubing is of extremely light gauge the
extra fine grade, which is known also as the quick running solder,
gives the best results.
Wire spelter, which comes in coils, has become very popular on account
of its lessened cost, its cleanliness, and also because it is not so
wasteful as loose spelter, and can be conveyed directly into the joint
by the operator as soon as it has reached the melting point.
[Illustration: EAGLE DROPPED FORGED FLUSH JOINT.]
Another method that is somewhat new is known as liquid brazing, which
is nothing really but a special treatment of the joint plunged into
molten spelter, and out of which the joint comes surprisingly free from
scale, a cleaning by a wire brush being about all the after treatment
necessary. The process is a secret one, and the surrounding joints are
covered with what is known as the anti-flux, so that the spelter will
not adhere there, but joints to be united, of course, are covered with
a liquid flux as in the old way.
The makers of the Union produce their flush joints by using what they
call pocket brazing. This mode requires the forming of a series of
pockets in the projecting ends of the brackets, which may be oval,
circular or of any desired shape, although the oval has been found
the most convenient. Before the tubing is completely fitted over the
bracket arm the pockets are filled with flux, and immediately upon the
application of the heat the brass begins to flow and with astonishing
evenness, so much so, in fact, that when after cooling, joints are
cut out, the brass is found as uniformly distributed as if laid on
with a brush. Moreover, no considerable amount of brass flows out of
the joint and no filling is necessary. Less heat is required for the
reason that the brass is placed where necessary and the parts need
not be dangerously heated to cause the brass to flow in. The pocket
corrugations are found to stiffen the machine to a marked degree. Taken
all in all it is a sure, clean and highly ingenious braze.
KANGAROO FRAME.
[Illustration: THE KANGAROO.]
Apropos of frames, we reproduce here a cut of the Kangaroo, which was
the first bicycle driven by chains. The earliest samples of the Rover
type antedated it, but there had been no previous commercial use of a
chain on a two-wheeler, for the Otto accomplished nothing commercially.
The Kangaroo was brought out in 1884, and attracted attention because
its makers were fortunate enough to break with it the 24-hour record,
which had been standing unchanged since the early years of bicycling.
This success, together with energetic pushing, gave the Kangaroo quite
a run for a couple of years, when the rear-driver put an end to its
career. It was brought to this country in 1885, but hardly obtained a
firm foothold for even the time being. The forks were bowed out widely,
there being no attempt to reduce width by lessening the “dish” of the
wheel, and consequently the tread was what would have been considered
in later years outlandishly wide. The wheel was usually 36, geared to
54, with a 22-inch wheel behind. The chief drawbacks were that the
sprocket bearings were ill-supported, as a shaft could not be run
through the wheel, and so they did not stand well under the twisting
strain; the backlash was unusual, all the objectionable features of
chain driving, which had not at that time been modified by improved
construction, being increased by having it on both sides. The Kangaroo
was also heavy and clumsy, and for some reason never satisfactorily
explained it had a peculiar liability to side-slip.
EXIT THE WOOD FRAME.
A difficulty which has hung about wood frames from the first is that
of the joints, nor could it ever be questioned that appearance was not
in favor of the wood frame, although, on the other hand, it must be
admitted that objections to appearance are soon overcome in cycling
construction if there is a good balance of points on behalf of a
thing. Perhaps the best-looking of the wood frames was that produced
by the “Old Tonk” people, who turned to account the beauty which may
be had from several layers of wood placed together. The wood frame
has succeeded quite as poorly abroad, and it will probably remain
forgotten until, some years hence, it comes up again as a novelty of
the season. The Bamboo Cycle Company has just failed in London, and
the _Irish Cyclist_ expresses surprise that it remained afloat so
long as it did. Not a single expert or a single cycling journal, says
the writer, ever referred to the bamboo frame except with disapproval,
although it was well advertised and the parties interested were ready
to pay for opinions. A considerable number of the bicycles were sold,
but the rarity of their appearance on the road suggests that even
those who bought them did not use them much. Now that the company has
failed, this writer says: “It is to be hoped that no one else will be
so foolish as to endeavor to accomplish the impossible task of proving
that a bamboo stick is as useful as a steel tube.”
The two working drawings of frame are from W. C. Boak of Buffalo, and
are reproductions of his blue-print drawings used in designing and
drafting 1898 frames, and show on the men’s model the exact drop (3
inches) of the crank-hanger from a line drawn between the front and
rear axles. The length of head is five inches, and the wheel base—the
distance between front and rear axles—is 41-11/16 inches. On the
ladies’ model the crank-hanger is dropped 2½ inches, and the head is
7½ inches, the wheel base being 41⅞ inches. The height of both frames
is 22 inches. The small numbers in the illustrations show the angles
of the frame and indicate the sizes of the tubing used. The designs
call for the use of D-shape tubing for the front and rear forks and
backstays and round tubing throughout the rest of the frame.
[Illustration]